my g got stored with no antifreeze this winter, when i went to it, it had no water! had sometime this morning and sorted out two, under the exhaust manifold and behind the cambelt, am i missing any??
I'd get the block pressure tested to find the leaks and then fix what you find wrong. It's not forced to be the core plugs - you might have cracked something.
get the block tested?? its not a guess, the core plug on the floor sorta said it was missing! all sorted now anyway only the two!